Various musical teaching systems have been devised in the past. See for example, the following U.S. Pat. Nos.:
Featherstone, 555,213 (1886) refers to a game board and playing chips with music notes arranged upon staffs with music note fractions.
Hoffmann, 1,114,139 (1914) refers to a game wherein a series of cards each has a pictorial representation of one octave of the piano keyboard. A second series of cards each represents one of the keys of a piano and has representations thereon characteristic of the particular piano key which it represents. Poems and pictures are referred to.
Grant, 1,100,824 (1914) refers to a shiftable color chart for positioning colors at the keys of a keyboard. "Do" is blue, and the chart is shifted across the keyboard so that, for example in the key of D, the blue "do" falls up on the piano key "D".
Hughey, 1,526,547 (1925) refers to an instruction set using distinctive colors to represent the different tones in a musical scale. Apparently identical, except differently colored, birds are shown, both with notes and with corresponding color keyed keys.
Anthony, 2,788,697 (1953) refers to a musical toy for actuating a ball to jump upwardly in response to actuating a tone, thus indicating visually the note of the tone being sounded.
Meadows, 2,791,147 (1957) refers to music instruction devices with indicia 60, 65 showing a teacher the specific actuation of a key performed by student.
Ney, 2,807,183 (1957) refers to keys of a dummy color keyboard 10 with colors on keys 42, and colored with symbols 40 on a staff, for teaching music.
Johnston, (1957) 2,814,230 refers to a piano teaching device. A note on a scale is illuminated when a corresponding key is depressed.
Kaufman, 2,944,349 (1958) of general interest, referring to comparison between a scale or chart and other information.
Siegel, 3,256,765 (1966) refers to a representation of a portion of a piano keyboard having a light behind each note, a frame in which a clef card carrying the clef symbol and a key signature card carrying sharp and flat signatures may be arranged in various manners, together with a note card carrying columns of holes representing the position of notes on the written notation, and an electrical system which automatically illuminates the appropriate key when a contact probe is inserted in one of the holes.
Zegers-Ten Horn, 3,742,642 (1973) refers to tone producing means 19-26; a geometric configuration 11-18, relates to a basic tone of a musical scale and the sound of a bell.
Bennett, 4,056,999 (1977) refers to overlay segments secured to the white keys of a piano keyboard to define clefs, lines, and spaces.
Patty, 4,559,861 (1985) refers to movable markers 40, 41, 42, 43, 44 having colors or numbers, for a stringed instrument as device for expediting musical instruction.
Schoerkmayr, 4,730,533 (1988) refers to a plurality of optical display means on each of the keys, the display means indicating the sequence of the keys to be actuated, for use by less gifted people.
Rosenberg, 5,011,412 (1991) refers to a keyboard 10. Colored lights go on when a key is correctly inserted. Letter code 40 is on the front end of each key, for use as an educational device.